1. Technical Field
The field of art to which this invention pertains may be generally located in the class of devices relating to grippers or gripping devices.
2. Background Information
It is known in the robot gripper art to provide parallel motion grippers for gripping workpieces to move the workpiece between selected positions. A disadvantage of some of the prior art grippers is that, although it is advertised that they provide a parallel motion, the gripper arms for such grippers move in an arc. Accordingly, if the gripper arms on such grippers have a V-shaped gripping jaw or finger, then it is necessary to reprogram the controls for the gripping apparatus for each size workpiece, since with different diameters, the V-shaped jaws will be at different positions along the arcuate path through which the gripper jaws are moved, making it necessary to reprogram the gripping apparatus for different diameter workpieces. There are some true parallel motion grippers on the market, but a disadvantage of the last mentioned grippers is that they basically work off a wedge means, which provides only a very short stroke or movement for the gripping jaws. A disadvantage of the last mentioned true parallel grippers is that they cannot be used for a wide range of different diameter workpieces and accordingly, they lack versatility. It is also known in the prior art to provide a true centering steady rest, having a center wear pad and two side wear pads for movement into supporting engagement with a workpiece, as shown in U.S. Pat. No. 4,399,639.